Reference:
STANDARDS OF THE EXPANSION JOINT MANUFACTURERS ASSOCIATION, TENTH EDITION, www.ejma.org

The following construction types are included in the design program:

1.     Unreinforced bellows

2.     Reinforced bellows

3.     Toroidal bellows

Fig. 4.13: Unreinforced bellows

 Fig. 4.44: Reinforced bellows

Fig. 4.15: Toroidal bellows

All 3 construction types might be used as a single bellows as well as universal bellows.